Unlike many other investments one can make, preferred stocks have more "knowns." By that I mean that these securities come with a variety of characteristics (as specified in the prospectus) that allow an investor to tailor their choices to the issues that are most consistent with their personal goals, resources and risk tolerance .
The biggest "known," of course, is that you know exactly how much you are going to be paid each quarter in dividend income and the exact day that the dividend cash is going to show up in your brokerage cash account (unlike common stocks, most mutual funds and ETFs). That known dividend amount and payment schedule also serves to lower the volatility of preferred stock prices since these characteristics remove most value speculators from the market (see "Why Falling Prices Should Be Welcomed by Preferred Stock Investors" for more on preferred stock price behavior).
Beyond the known income amount and payment schedule, preferred stock investors also know how long the issuing company is obligated to continue making those payments for and what happens if they fail to do so. Preferred stocks with the "cumulative" dividend characteristic, for example, require the issuing company to ultimately make up any skipped dividends to you (short of a bankruptcy); their obligation to you accumulates (see "Cumulative Preferred Stock Dividend Characteristic Saves Citizens Republic Shareholders" for a cumulative preferred stock case study).
Moody's Versus the Market
In addition to having more "knowns," preferred stocks are rated by companies like Moody's Investors Service and Standard & Poors . Rating agencies and preferred stock investors, while using different methods, usually judge the investment risk of a preferred stock with very little disparity. Where agency ratings come in the form of a quantitative rating on a scale , investor conclusions about risk are reflected in today's market price (and hence yield).
This chart compares the risk assessment made by Moody's versus how the market is assessing the risk of these same preferred stocks (as reflected by current yield). Each diamond on the chart is a preferred stock. The preferred stocks shown on this chart are very similar in that they all meet the characteristics shown in the Included and Excluded lists seen beneath the table.
Looking at the table under the chart, while all of these securities are rated as investment grade by Moody's, the higher risk preferred stocks provide a higher current yield - no surprise there .
But this chart illustrates why investors (including preferred stock investors) are often encouraged to go a step or two beyond agency ratings when shopping for purchases. The fact that preferred stocks have more "knowns" than many other types of investments allows you to do so .
For example, notice the yield spread at the Baa2 risk level. The two preferred stocks shown as green diamonds are both assessed by Moody's as having the same risk and, looking over their specific characteristics, both of these securities do, in fact, have a lot in common (see the Included and Excluded characteristics listed below the table). So why the massive 3.3 percent yield difference?
The top green diamond is NEE-F from NextEra Energy (NYSE:NEE). NEE-F offers a whopping 8.75 percent dividend rate (coupon). A preferred stock with the characteristics listed below the table that is offering an 8.75 percent dividend rate in today's 7 percent market should be selling for about $31.25 per share but NEE-F is selling today for a mere $25.63. What a bargain, right?
But this is where a closer look beyond agency ratings can be helpful.
Looking at the current yield of NextEra's four other call-protected preferreds, the company could probably issue a new Baa2-rated preferred today at about 6.5 percent and use the proceeds to redeem NEE-F. Issuing a new preferred and using the proceeds to redeem NEE-F would save NextEra about $8.5 million dollars per year in dividend expense. That means that NEE-F is highly likely to be called when its March 1, 2014 call date arrives. In that event, shareholders will receive the security's par value ($25 per share) in cash plus the final quarter's dividend payment which computes to a maximum redemption amount of $25.55 per share to shareholders.
NEE-F's market price is being set accordingly at $25.63. It is the likelihood of redemption that is creating this security's seemingly attractive market price and 8.53 percent current yield, more so than its Baa2 rating .
The bottom green diamond at Baa2 is PBI-A from Pitney Bowes (NYSE:PBI). PBI-A offers a miserly 5.25 percent dividend rate (coupon) and is selling for $25.02, right at its $25 par value (at par, the security's current yield will equal its declared dividend rate, 5.25 percent in this case).
PBI-A does not become callable until November 27, 2015 so it does not suffer from the price distortion of an approaching call date that we saw with NEE-F.
But with the average Baa2 yield at 6.7 percent in today's preferred stock market, why is PBI-A being priced such that it only returns a 5.25 percent current yield?
PBI-A currently has two problems - it is unlikely to ever be redeemed by Pitney Bowes and, accordingly, it is overpriced at $25.02.
Historically, the dividend rate offered by these preferreds with the characteristics listed under the table ranges between 6 percent and 9 percent with the long-term average being 7 percent. At 5.25 percent, PBI-A is providing historically cheap money to Pitney Bowes making it unlikely that the company will ever redeem PBI-A prior to its November 27, 2022 maturity date.
Even for those who are content to make 5.25 percent on their money until late-2022, looking at the Baa2 stack on the chart shows us that PBI-A is overpriced at $25.02. To confirm that the market has overpriced PBI-A, Pitney Bowes also offers PBI-B, a nearly identical preferred but PBI-B has a much higher 6.7 percent dividend rate and a March 7, 2018 call date. PBI-B is selling for $24.28 today (August 30), $0.72 below its $25 par value.
Investors are usually trying to determine the likelihood of a bankruptcy of the company they are considering investing in while rating agencies are trying to quantify creditworthiness. While such ratings are meaningful, the market's definition of risk can vary from what agency ratings are measuring, leading to the yield spreads illustrated by the above chart (see "Moody's And Preferred Stock Investors View Same Market But See Very Different Risks" for a similar analysis from last April).
As the table below the chart quantifies, the preferred stock market is transitioning back to one that favors buyers - higher returns available for lower market prices. The alternatives available to us are the best that we have seen in over two years with several high quality issues now offering 7 percent dividend rates (coupon) for sub-$25 market prices.
Preferred stock investors have an enormous advantage since preferred stocks comes with more "knowns" than many other types of investments. While agency ratings are helpful, going a step or two further can help separate the real candidates from the pretenders.
 Source for all preferred stock data in this article: CDx3 Notification Service database and Preferred Stock Investing, Fifth Edition (PreferredStockInvesting.com). Disclosure: The CDx3 Notification Service is my preferred stock email alert and research newsletter service and includes the database of all preferred stocks and exchange-traded debt securities traded on U.S. stock exchanges used for this article.
 We learned during the Global Credit Crisis that agency ratings were imperfect for a variety of reasons. Shortcomings of both mathematics and character led to grossly incorrect ratings in too many cases. But historically, short of such crisis conditions, agency ratings of securities have served millions of investors all over the globe very well for many decades. And as imperfect as these ratings are, the fact is that most investors have little choice but to use such ratings as a proxy for investment risk.
 Moody's investment grade ratings, strongest to weakest: Aaa, Aa1, Aa2, Aa3, A1, A2, A3, Baa1, Baa2 and Baa3.
 The "current yield" values seen here use the same current yield formula that you see in your brokerage account or other websites that show yield for dividend-paying securities. Current yield does not consider the potential for a future capital gain or loss nor the duration of your investment but, rather, is intended to be used for comparison purposes here. For more on the strengths and weaknesses associated with the various methods for calculating the return from a preferred stock investment see "Preferred Stock Investors: What Is Your Rate Of Return?"
 The preferred stock information needed to do the type of due diligence discussed in this article is available from a variety of sources depending on how much work you want to do yourself. While the CDx3 Notification Service (used for this article, see Footnote #1) is a full-service resource, others are more oriented for do-it-yourselfers. QuantumOnline's site (Quantumonline.com), which requests a fee on the honor system, can be very helpful but does not provide downloadable data, market prices, ex-dividend dates, yields, email alerts or access to experts.
 Using a different return calculation that considers the duration of the investment, such as Effective Annual Return or Yield to Call, would show a lower value for securities that are closer to their call dates. See Footnote #4.
Disclosure: I have no positions in any stocks mentioned, and no plans to initiate any positions within the next 72 hours. I wrote this article myself, and it expresses my own opinions. I am not receiving compensation for it. I have no business relationship with any company whose stock is mentioned in this article. Securities identified within this article are for illustration purposes only and are not to be taken as recommendations.